The technology disclosed herein generally relates to optical networks that enable communication between electrical components.
Optical networking using plastic optical fibers may provide advantages over networking using copper or other metal wiring. Categories of plastic optical fiber include plastic-clad silicon optical fiber, single-core plastic optical fiber, or multi-core plastic optical fiber. Plastic optical fiber networking may have lower installation and maintenance costs. Moreover, because plastic optical fibers are lighter than the metal wiring that would be needed to carry an equivalent amount of data, using plastic optical fibers may result in appreciable weight savings. The weight savings may be significant for networks onboard vehicles, such as aircraft, where the weight savings may result in reduced fuel consumption and lower emissions.
In some scenarios, it is desirable to connect a number of line replaceable units to each other. For example, a number of line replaceable units in the forward section of a vehicle (e.g., an aircraft) may need to be connected to a number of line replaceable units in the aft section of the vehicle. Connecting each line replaceable unit to every other line replaceable unit could result in an unreasonably large number of connections between line replaceable units. Additionally, many of the connections between line replaceable units may be long, resulting in optical losses. If all of these connections were in the form of copper wires, the resulting space and weight of the connections could be burdensome for the vehicle. Electrical data buses have been used to connect line replaceable units. A single optical data bus can eliminate some of the weight and size of electrical connections between line replaceable units. In general, optical communication fibers, such as glass optical fibers and plastic optical fibers, can be lighter and contained in smaller spaces than electrical wiring. However, implementing optical communication systems is not as simple as merely replacing all electric wiring with optical fibers.
Plastic optical fibers have high transmission capacity, excellent immunity to electromagnetic interference-induced noise, light weight, high mechanical strength, and outstanding flexibility. Due to these properties, plastic optical fibers are used in data communications, as well as decoration, illumination, and similar industrial applications. Plastic optical fibers are also larger in diameter as compared to glass optical fibers. Due to their larger diameters, plastic optical fibers have greater tolerance for fiber misalignment than glass optical fibers have. Because of this large misalignment tolerance, plastic optical fiber-based networks have lower maintenance and installation costs. In aerospace platforms, plastic optical fibers also greatly reduce the cost of connectors and transceiver components used in an avionics network.
Currently, some optical data bus architectures (e.g., an ARINC 629 plastic optical fiber (POF) data bus) employed in aircraft require an individually packaged optical-electrical media converter for each channel. They also require individually packaged passive optical star couplers. These individually packaged units are interconnected together by fully jacketed POF cables.
As used herein, the term “star coupler” comprises one or more devices of a type that receives a plurality of optical signals at an input face via respective input optical fibers and outputs respective portions of each received optical signal to each of a plurality of output optical fibers optically coupled to an output face of the device. Thus each output optical fiber receives respective input optical signals from all of the input optical fibers. It is known to combine two devices of this type to form a star coupler that can be optically coupled to the transmitters and receivers of a plurality of optical-electrical media converters to enable a plurality of electronic components (such as line replaceable units), which are respectively electrically connected to the optical-electrical media converters, to communicate with each other.
An existing solution uses dual symmetric star couplers having input and output faces optically coupled to 1-mm-diameter plastic optical fibers, which plastic optical fibers are also connected to transmitters and receivers of respective optical-electrical media converters. In a known case, each receiver of an optical-electrical media converter comprises a photodetector having a diameter less than 1 mm (e.g., 0.4 mm). Because the 1-mm-diameter output plastic optical fibers optically coupled to the receivers are larger than the photodetector, this mismatch produces an optical coupling loss.
There is a need for a solution that reduces, if not eliminates, optical coupling loss due to mismatched sizes of POF end faces and photodetectors incorporated in receivers of optical-electrical media converters.